Electromagnetic switching mechanism in an electric pump



p 1966 w. c. EBERLINE ETAL 3,273,086

ELECTROMAGNETIC SWITCHING MECHANISM IN AN ELECTRIC PUMP Filed Jan. 8, 1964 2 Sheets-Sheet l we /4o 6 INVENTORS W/ZZ/AM C. 'BA'RA/A E AZTO/V J? O'CO/V/VOR /60 BY I M, E; i

p 1966 w. c. EBERLINE ETAL 3,273,086

ELECTROMAGNETIC SWITCHING MECHANISM IN AN ELECTRIC PUMP Filed Jan. 8. 1964 2 Sheets-Sheet 2 32 Y X Y 4? A94 J2 Y 1448/ A38 L15 M mg;

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ATTOR/VAFKS United States Patent "ice 3,273,086 ELECTROMAGNETIC SWITCHING MECHANISM IN AN ELECTRIC PUMP William C. Eberline and Alton J. OConnor, Cass City, Mich., assignors to Walbro Corporation, Cass City,

Mich., a corporation of Michigan Filed Jan. 8, 1964, Ser. No. 336,575 6 Claims. (Cl. 335 -87) This invention relates to improvements in an electric pump and more particularly to that type of pump which is utilized for the pumping of fuel to an internal combustion engine. The pump is an electromagnetic or solenoidactuated device in. which the switch mechanism for controlling the pump strokes is entirely self-contained within the pump housing It is an object of the invention to provide a quiet operating, long-life pump of the type described for small gasoline engines, such as outboard engines and for use on automotive engines and tractor engines, for example. The pump is generally of the type having a capacity from 15 to 40 gallons per hour.

It is an object of the invention to provide a pump which is easily assembled and readily serviced in the event of need for repair.

Another object is the provision of an improved switching mechanism which is quieter in operation and which has a considerably longer life than previous designs.

It is a further object to provide a switching construction completely housed inlthe pump which is quieter in operation and a pump construction which has a lengthened stroke to increase the capacity.

Other objects and features of the invention relating to details of construction and operation will be apparent in the following description and claims.

Drawing-s accompany thedisclosure and the various views thereof may be briefly described as:

FIGURE 1, a vertical section through the pump showing the relationship of the various elements of the assembly.

FIGURE 2, a sectional view on line,2-2 of FIGURE 1.

FIGURE. 3, a partial section taken on line 33 of FIGURE 2.

FIGURE 4, a modified sectional view of a portion of the pump showing the use of a bellows-type diaphragm.

Referring to the drawings:

In FIGURE 1, a housing 20 has an inlet 22 and an outlet 24 with suitable inlet and outlet valve assemblies 26 and.28. whichadjoin a common pumping chamber 30. The pumping chamber isformed in a secondary housing 32 sealedto the housing '20 by a gasket 34 The valves 26; andf28 are positioned in adjacent openings in the housing 32. The housing 32 is fastened to a solenoid and switch casing shell 36 which has an internal top plate 38 recessed in a small groove 40 on the inside of the top edge of the. casing 36. A gasket 42 seals housing 32 to the casing 36. An annular recess 44 receives a ring 46 which seats on the periphery 48 of a pumping diaphragm 5.0 which has a flexible portion operating within the ring 46. v v V Within the casing shell 36 is a solenoid-winding shell 52 having a base plate 54 which is solidly held in the casing 36 by screws 56 (FIGURE 2). The plate 54 seats againstshoulders (not shown) at the top of segmental inserts 58 in the casing shell (see FIGURE 2) Within the solenoid shell 52 is atop solenoid plate 60 positioned by small indentations 62, the solenoid winding'64 being formed around acylindrical sleeve 66. An armature guide sleeve 68 has one end 70 flanged into a beveled opening in base plate 54 arid another end 72 extending through an opening in the top plate 60. and flanged over the edges of opening.

3,273,086 Patented Sept. 13,. 1966 The solenoid housing shell 52 is preferably formed of magnetic material, and the plate 54 is similarly formed. The plate 60 can be formed of a fiber board material. The winding 64 has, for example, for a 6-volt pump, 300 turns of 18 gage copper wire; for a l2-volt pump, it can be 500 turns of'21 gage copper wire. The armature guide sleeve 68 is preferably hard chrome plated to provide a wearing surface for the armature 74 mounted on a shaft 76 threaded at the top end 78)) be received in a threaded apertureof a cylinder 80.

The center of the diaphragm 50 overlies the top end of the cylinder 80 and is retained thereon by a washer 82 held by a screw 84'also threaded into the passage in the cylinder 80. An inverted bell-shaped element 86, fastened centrally between the armature 74 and the cylinder 80, has an outwardly extending flange 88 of a dimension that it will be received within the shell 52. This flange and the walls of the elements 86 serve as a seat for a return spring 90 seating at its bottom end on the plate 60.

It will be seen that vertical motion of the armature in the solenoid winding will cause a pumping action of the diaphragm 50 creating alternately low pressure conditions and high pressure conditions in the chamber 30 in a manner to move gasoline through the pump from the inlet to the outlet.

Turning now to the electrical portions of the magnetic coil circuit, it will be seen that the shaft 76 projects downwardly through the armature 74, it having a reasonably tight fit in the armature and there being a plastic washer surrounding the shaft directly below the armature 74. The moving switch element of the circuit has a flat central portion 102 apertured to receive the bottom end of the shaft 76, theaperture being of sufiicient size to clear the shaft in its movement. A steel washer 104 is secured to the flat portion 102 for improving the point control of the system in a manner to be described. This washer is also apertured to clear the shaft 716. The flat portion 102 of the switching element carries back into a transverse bar portion 106' (see FIGURE 2) and extending from this bar portion 106 are two point carrying legs V108 and 110;, these legs extending downwardly from the bar portion 106 as shown in FIGURE 1 and then transversely astraddle pin 76 in short point carrying tabs 112.

Mounted on these tabs are wear resistant conductive points 114. Below the flat portion 102 is a plastic washer 116 which surrounds the shaft 76 and serves as a seat for a spacer spring 118'surrounding the shaftand fitting at its bottom end on another plastic washer 120. A sheet metal nut 122 is threaded on the end of the shaft 76 against washer120.' The transverse bar portion 106 of the switch element is mounted on a cylindrical shank 124 of a screw having a head 126 and a threaded portion 128, this threaded portion being anchored in a tapped hole in the plate 54. Around the shank 124 is a compression spring 130 seating at the top'against the bar 106 and at the bottom against the head, of the screw 126. This is preferably a brass screw while the switch element 102 is preferably formed of a relatively stiff steel. Interposed between the bar portion 106 and the lower surface of the plate 54 is a thin sheet 132. of a bearing material, one example of which is called Armalon. This bearing material provides a longer life for the parts and insures a quieter operation. The bar 106 is also dimpled at 134 and 136;, these dimples forming small upward projections 138 which engage in spaced recesses in plate 54. The parts are shown in inverted position in FIGURE 3 as a section of the bottom of the unit illustrated in FIGURE 2. Thus, the bar is stabilized in its motion so that the steel washer 104 is fitted within the armature guide sleeve 68.

It will be seen that downward motion of the armature 74 will cause the plastic washer 100 to contact the washer 104 shifting the central portion 102 and the arms 108-110 downwardly against the action of the spring 130. The spring 130 is preferably formed of a beryllium copper material and serves secondarily to provide a positive grounding action between the conductive bar portion 106 and the brass screw 126, this being a ground connection for the switch system. The spring 118 is also preferably a chrome silicon spring to add to the life of the unit and the shaft 76 is preferably formed of stainless steel for prevention of corrosion and to provide a longer life. The steel washer 104 being magnetic tends to attract to the armature when the system is energized, thus improving the action of the switching mechanism. The spring 118 is provided in place of a previously used solid spacer. It serves to cause a quick breakaway action upon the return stroke of the armature, thus reducing arcing of the points to a minimum and giving better point control.

The spring 118 is preferably a barrel-shaped spring so that each coil telescopes into the next adjacent coil. The entire spring can accordingly collapse without a jamming contact.

On the left-hand side of the plate 54, as shown in FIG- URE 1, is a plastic mounting bar 140 which seats against the bottom of plate 54 and serves as a solid support for a bifurcate point holder plate 142 having arms 144 and 146 extending toward the center of the assembly ast-raddle pin 76 and each serving as a mount for a contact point 148 to engage the points 114 on switch arms 108-110. The material from which the point holder plate 142 is formed is preferably of relatively stiff material so that there is relatively little deflection, if any, when the arms 108-110 contact it upon lifting of the armature 74. The plate 142 is held up against the mounting block 140 by a plastic screw 150 which passes through the bar 140 and anchors in a tapped hole in the plate 54. Small projections 151 on the bottom of the plastic bar 140 project through holes in the plate 142 to stabilize it in position.

A washer-like head on this screw 150 contacts the plate 142 and a narrowed head portion 152 serves as a seat for an apertured metallic contact tab 154 as shown in FIGURE 2. Soldered to one end of this contact tab is a lead wire 156 leading to one end of coil 64. The other end of the coil '64 is connected through a lead 158 to the plate 142 which carries the contacts 148. A source of electrical power is introduced into the system through a conductive screw 160 which passes through a non-conductive plastic mount 162 in a hole 164 in the base of the casing shell 36. The conductive screw 160 has a head portion 166 which projects through the plastic mount 162 and serves as a seat for a conductive spring 170 which seats at its top end against the conductor tab 156 and preferably with frictional engagement with the head 152 of screw 150.

It will be seen that the entire solenoid and armature assembly can be inserted into the shell casing 36 with the Spring 170 carried on the end of the screw 150. The spring 170 can then be piloted into position around the conductive screw head 166 so that outside current can be carried into the solenoid winding. With the armature in the up position, as shown in FIGURE 1, the contacts 114 and the contacts 148 are touching. Current is thus carried to the coil through the ground screw 124 and the general housing assembly. Energization of the coil causes the armature 74 to move downwardly so that the washer 100 will contact the washer 104 and depress the central portion 102 fastened to the switch plate bar 106. This depresses the arms 108-110, breaking the contacts and causing de-energization of the coil. As this process continues, the diaphragm 50 is fluctuated up and down to cause a pumping action through the chamber 30.

In FIGURE '4, a modified type of structure is shown utilizing a bellows 180 having an annular locking rim 182 suitably retained in an annular recess in a'plate 184. A

4 cylindrical nut 186 anchors to a threaded end of a shaft 188 to clamp the other end 190 of the bellows against the bottom of the flanged bell 86. The remainder of the construction is the same as previously described with reference to FIGURES 1 to 3.

In the operation of the pump, the use of the stiff arms 144 eliminates the rubbing of the contacts 114 and 148, thus eliminating unnecessary wear on these points. Some very slight deflection of arms 108 and 144, which is inevitable, will cause a certain amount of rubbing which will keep the points clean and remove any oxidation. In addition, it will be seen that energization of the solenoid will attract steel washer 104,-holding it up until the armature moves solidly down to cause a quick break of the arms 108110 downwardly. Thus, even though the downward motion of the armature is relieving the upward pressure exerted by spring 118, the point arms will not move until solid contact is made between washer and wash er 104. This causes a sharp break of the electrical conact and prevents destructive arcing.

The normal action of spring 130 is to urge the flat bar portion 106 flat against the plate 54. In this position, in the absence of other forces on the unit, the points will be spaced from each other. On the upstroke of the armature by reason of the action of spring 90, the force of spring 118 in compression overcomes the pressure of spring 130 causing the points to close. Then, as the solenoid is energized, the downward motion of the armature will relieve the pressure of spring 118 and make it possible for spring 130 to tend to open the points but this is counteracted by the magnetic force on steel washer 104 which holds the points in contact until there is a positive mechanical break. 1

At the completion of the downward stroke of the armature, the spring 118 is out of action completely because the downward motion of the bottom supporting washer relieves all compression on this spring. The spring 130, however, is compressed to some degree at this stage and will return the points in the direction of contact as the solenoid moves upwardly under the action of spring 90. The points will be positively closed when the spring 118 is again brought into action when it is compressed against the washer 116.

We claim: v

1. In a solenoid actuated pump wherein a flexible diaphragm is actuated in a valve pumping chamber, that improvement in an automatic switching mechanism which comprises:

(a) an actuating solenoid,

(b) opposed contact points for opening and closing a circuit to energize and de-energize said actuating solenoid,

(c) first means mounting one of said points in space adjacent the operating axis of said solenoid,

((1) second means movably mounting the other of said points wherein it may move to and from contact with said first point,

(e) an armature movable axially in said solenoid from a retracted to an extended position when the solenoid is energized having a portion positioned to contact and shift said second means in the extended position, and

(f) means connecting said armature and said second means resiliently to effect motions of said points toward each other to contact position and means magnetically associating said second means and said armature to bias said points toward each other prior to contact of said armature with said second means to cause positive separation of said points.

2. A solenoid circuit control mechanism as defined in claim 1 in which said second means comprises a plate mounted generally in a plane transverse to the axis of the solenoid, means for mounting said plate for limited motion in a direction generally parallel with said axis, said means to associate said armature resiliently and magnetically with said second means comprising a shaft on said armature transfixing said plate, means resiliently associating said shaft and said plate to bias said plate to a points closed position and magnetic means on said plate mounted in the vicinity of the armature to lie in the magnetic field of said solenoid to bias said plate toward a points closed position during energization of said solenoid.

3. In a solenoid actuated pump wherein a flexible diaphragm is actuated in a valve pumping chamber, that improvement which comprises:

(a) a solenoid-armature assembly in which the armature operates on the axis of the solenoid from a retracted position in a de-energized condition of the solenoid to a projected position is an energized condition of the solenoid,

(b) opposed contact points for opening and closing a circuit to energize and de-energide said solenoid,

(c) first means on said assembly mounting one of said points in space adjacent the operating axis of the solenoid,

((1) second means on said assembly movably mounting the other of said points wherein it may move to and from a points open to a points closed position,

(e) resilient means on said assembly urging said second means in a direction away from a points closed position,

(f) extension means extending from said armature to said second means,

(g) resilient means connecting said extension means and said second means to bias said second means to a points closed position in the de-energized condition of the solenoid,

(h) means on said armature to contact and move said second means to a points open position in the energized condition of the solenoid, and

(i) magnetic means on said second means positioned in the field zone of said armature wherein to be magnetically attracted to said armature and solenoid in the energized condition to bias said second means to a points closed position prior to contact by said armature in its movement to projected position.

4. In a solenoid actuated pump wherein a flexible diaphragm is actuated in a valve pumping chamber, that improvement which comprises:

(a) a solenoid-armature assembly having a switch mounting base plate in which the armature operates on the axis of the solenoid from a retracted position in a de-energized condition of a solenoid to a projecting position in an energized condition of a solenoid,

( b) opposed contact points for opening and closing a circuit to energize and de-energize said solenoid,

(c) a first plate means mounted on said solenoid assembly in insulated relation thereto carrying one of said points in space adjacent the operating axis of said solenoid,

(d) a second plate means on said assembly movably mounting the other of said points wherein it may move to and from a points open to a points closed position,

(e) resilient means on said assembly urging a portion of said second plate means flat against said base plate in which position said points are spaced from each other,

(f) an axial pin extending from said armature to a portion of said second plate means,

(g) a spring surrounding and anchored at one end of said pin by an anchoring means and bearing against another portion of said second plate means to urge said second plate means to a points closed position in the de-energized condition of the solenoid,

(h) pusher means on said armature to contact and move said second means to a points open position in the energized condition of the solenoid, and

(i) magnetic means on said second means positioned in the field zone of said armature wherein to be magnetically attracted to said armature and solenoid in the energized condition to bias said second means to a points closed position prior to contact by said armature in its movement to projected position.

5. A device as defined in claim 4 in which said opposed contact points each comprise a pair of points positioned in substantially .the same plane, and each said first and second plate means has bifurcate portions to mount said pairs of points in spaced relation, said second plate means being mounted on said assembly by transfixing spring post passing through an aperture in said second plate means of larger diameter than said post, said resilient means on said assembly surrounding said post and bearing against said second plate means, and interfittingprojections between said base plate and said second plate means to confine said parts in a relative position while permitting a floating relation to facilitate full point contact between the opposed pairs of points.

6. A solenoid assembly as defined in claim 4 in which a retraction spring is interposed between said solenoid and a portion of said armature and held in compressed condition therebetween, said solenoid and armature being retained in assembled relation by said anchoring means acting in conjunction with said second plate means.

References Cited by the Examiner UNITED STATES PATENTS 2,104,190 1/1938 Dettar 200-111 2,104,399 1/1938 Kuhn 200-111 2,519,607 8/ 1950 Steynor 2001 11 X 2,650,277 8/1953 Reck et al 200 3,001,099 9/1961 Larkey 200-111 X BERNARD A. GILHEANY, Primary Examiner. T. D. MAcBLA-IN, Assistant Examiner. 

1. IN A SOLENOID ACTUATED PUMP WHEREIN A FLEXIBLE DIAPHRAGM IS ACTUATED IN A VALVE PUMPING CHAMBER, THAT IMPROVEMENT IN AN AUTOMATIC SWITCHING MECHANISM WHICH COMPRISES: (A) AN ACTUATING SOLENOID, (B) OPPOSED CONTACT POINTS FOR OPENING AND CLOSING A CIRCUIT TO ENERGIZE AND DE-ENERGIZE SAID ACTUATING SOLENOID, (C) FIRST MEANS MOUNTING ONE OF SAID POINTS IN SPACE ADJACENT THE OPERATING AXIS OF SAID SOLENOID, (D) SECOND MEANS MOVABLY MOUNTING THE OTHER OF SAID POINTS WHEREIN IT MAY MOVE TO AND FROM CONTACT WITH SAID FIRST POINT, (E) AN ARMATURE MOVABLE AXIALLY IN SAID SOLENOID FROM A RETRACTED TO AN EXTENDED POSITION WHEN THE SOLENOID IS ENERGIZED HAVING A PORTION POSITIONED TO CONTACT AND SHIFT SAID SECOND MEANS IN THE EXTENDED POSITION, AND (F) MEANS CONNECTING SAID ARMATURE AND SAID SECOND MEANS RESILIENTLY TO EFFECT MOTIONS OF SAID POINTS TOWARD EACH OTHER TO CONTACT POSITION AND MEANS MAGNETICALLY ASSOCIATING SAID SECOND MEANS AND SAID ARMATURE TO BIAS SAID POINTS TOWARD EACH OTHER PRIOR TO CONTACT OF SAID ARMATURE WITH SAID SECOND MEANS TO CAUSE POSITIVE SEPARATION OF SAID POINTS. 